The present invention relates to a manufacturing method for forming an integrated circuit device and to a corresponding integrated circuit device. Although in principle applicable to arbitrary integrated circuit devices, the following invention and the underlying problems will be explained with respect to integrated memory circuits in silicon technology.
Memory circuits of today usually comprise fuses in order provide redundancy elements. Said fuses are e.g. used in order to activate said redundancy elements, e.g. by irradiation of laser energy. Said fuses may be located in a process level which is below a contact pad metal level. Both for the fuse level and the contact pad metal level, contact holes are formed during the fabrication process.
It has been attempted to open the contact holes for the fuse window and the pad simultaneously. If the fuses are located in a metal level one layer below the pad metal level, such a simultaneous etching step would use the metal pad as an etch stop.
For pads made of copper-containing materials or copper, a simultaneous etching step may lead to corrosion of the exposed copper comprising pad. Additionally, copper damascene layers usually have a cap layer (top barrier) in order to prevent copper diffusion and achieve the electro-migration and stress migration performance needed for reliability purposes. E.g. silicon nitride or silicon carbide films are used as cap layer material. It would be desirable that the etching steps of opening the fuse-window and the contact pads could be made simultaneously without having the problem of pad corrosion.